Effects of cyclic carbonation and chloride ingress on durability properties of mortars containing Trass and Pumice natural pozzolans

Abstract

With an increase in CO2 emission, corrosion of reinforcement as a result of carbonation has become more significant to researchers besides corrosion due to chloride ion ingress. Many structures are exposed to coupled effects of carbonation and chloride attack; therefore, investigating the effect of this combined attack on the durability of concrete is a vital subject. Also, the use of supplementary cementitious materials (SCMs) has become more common due to their contribution to concrete's properties. In this study, the combined effect of chloride attack and carbonation on the durability of mortars containing SCMs was studied. Two natural pozzolans (Pumice and Trass) were used as cement replacements in mortar mixtures with three w/b ratios of 0.485, 0.44, and 0.4. Four exposure conditions, namely normal (immersed in lime‐saturated water), chloride attack, carbonation, and cyclic carbonation and chloride attack were considered. Compressive strength, carbonation and chloride penetration depth, capillary water absorption, surface electrical resistivity, and chloride diffusion tests were performed. The results indicate that while carbonation depth is reduced in the combined attack environment, it imposed a more severe corrosive condition in comparison to pure immersion in saline water by increasing the diffusion coefficient up to 500%. Also, addition of pozzolans showed the potential to reduce the diffusion coefficient of the mortars as much as 76% pointing out that mortars without pozzolans were more vulnerable to this combined attack environment. Furthermore, cement replacement with Trass and reduction of w/b showed to be beneficial in reducing the destructive effects of the combined environment.

Structural Design and Performance Optimization of Green Concrete Based on Recycled Pumice and Modified Rubber Powder

“…First, carefully select the raw materials, including cement, aggregate (such as sand and gravel), water, and additives (such as Si plate 40 dikyl benzene sulfonate sodium), based on the required concrete strength and environmental conditions. Next, mix the raw materials in a specific amount of water and other additives until they are evenly blended [17,18]. The process begins by pouring the mixed concrete into the mold to fill it completely and eliminate any bubbles or gaps.…”

A Comprehensive Review of the Effects of Different Simulated Environmental Conditions and Hybridization Processes on the Mechanical Behavior of Different FRP Bars

“…The corrosion of steel bars is a major problem that causes a heavy cost for repairing or replacing concrete elements. Thus, it is not feasible to use steel bars as a reinforcement in seawater sea-sand concrete because of the corrosion [2][3][4][5][6][7][8] of these types of bars [9][10][11][12][13][14], as well as the aggressive environmental conditions that exist near to coastal areas [15][16][17][18][19][20][21][22][23][24]. Seawater and sea sand contain chloride ions.…”

Effect of Equal Volume Replacement of Fine Aggregate with Fly Ash on Carbonation Resistance of Concrete

“…Carbonation occurs when acidic gases such as CO 2 form carbonic acid in the concrete, and react with alkaline substances such as the cement hydration product Ca(OH) 2 to form CaCO 3 , which reduces the alkalinity of concrete [15][16][17]. Currently, carbonation becomes more severe with an increase in CO 2 concentration in the environment [18]. However, higher requirements have been proposed for the anticarbonation performance of concrete.…”